The present invention relates generally to the field of dental implants and, in particular, to a new and useful soft-tissue preservation abutment arrangement and method.
General Considerations and Problems to Overcome
The tooth is a structure of the oral cavity which is vital to the capability of chewing and important to the general well-being and appearance of people. Anatomically, the tooth resides within the oral cavity, firmly anchored within the upper and lower jaws (maxilla and mandible). Human teeth reside within two distinct anatomic regions of the jaws; the apical inferior portion of the tooth (the root) is connected to the jaw via an attachment called the periodontal ligament. We will here define this portion of the tooth that is connected to the bone as the “bone-zone” or hard tissue zone of the tooth. Second, the superior portion of the tooth (the anatomic crown) is connected to the jaw in the soft-tissue or gingival region of the jaw defined as the “tissue-zone” or soft tissue zone. The anatomic crown is demarcated as that portion of the tooth superior to crest of bone and it will include a small portion of the root superior to the crest of bone as well as the clinical crown that is visible. The tissue-zone forms a soft-tissue collar around the neck of a tooth. This tissue-zone connection (i.e. soft-tissue to tooth attachment) is composed of gingival fibers that insert into the superior aspect of the root surface; specifically, hemidesmosmal cell attachment to the root and crown forming a biological adhesion of the sulcular epithelium (gingival tissues) to the surface of a tooth.
The tissue-zone connection plays a critical role in maintaining health of the oral cavity. It does this by preventing the ingress of microbes and foreign substances into the body by providing a “biologic-seal” at the interface of the tooth-jaw connection at the tissue-zone. This functional attachment of the soft-tissue to the surface of the tooth should be fully appreciated as a critical defense barrier. As without the presence of this soft-tissue biologic seal the underlying bone would be vulnerable to numerous invasions of various foreign substances.
In addition, the tissue-zone plays an essential role in maintaining and preserving the dental esthetics of the smile. This same tissue-zone represents the peaks (papillae) and valleys of the soft-tissue gingival that surround the neck of each and every tooth. It is the spatial relationship of tooth form and color with healthy soft-tissue gingival architecture that are known as the essential building blocks of dental esthetics as we know it. Experts of dental esthetics have called the soft-tissue gingiva “the frame” of the picture, and regard the teeth as the “subject matter” of that painting. Disregarding the frame of a painting would certainly impact the overall esthetic appearance being viewed, and the same is true with respect to the gums and teeth. The loss or the alternation of anatomic structures of the tissue-zone has been shown to lead to an inferior esthetic outcome in addition to causing a potential risk of disease for the patient.
The tooth and its attachment to the jaw is subject to numerous pathogens over the lifetime of a patient, particularly due to trauma/fracture, endodontic failure, decay, localized periodontal disease, etc. Any of these conditions can lead to the eventual need for removal of either a single tooth or multiple teeth. The removal or extraction of a tooth or teeth will result in a radical morphologic change to the anatomy as well as the potential exposure of the internal tissues (connective tissues and underlying organs) of the body to invasion by foreign substances.
The extraction of a tooth results in a cascade of changes depending on how this procedure is performed. Tooth removal in the past has been a highly traumatic surgical procedure. It was not uncommon for an oral surgeon to fully reflect the gingival tissues as a surgical flap to expose the underlying tooth and bone to aid in the ease of access and visualization of the tooth to be removed. It is during this surgical reflection of the gingival soft-tissues that the normal anatomy of the tissue-zone would be radically altered and permanently changed. Destruction of the normal architecture of the gingiva occur as surgical instruments were used to cut, tear, crush and rip the attachment fibers between the tooth and soft-tissues of the tissue-zone. In accordance with gingival surgical flap surgery, closure of a surgical flap is accomplished with the placement of sutures to close the wound created. Primary (or complete) flap closure is highly desirable to ensure the re-establishment of a biologic-seal of the soft-tissue to prevent ingress of foreign bodies to the host.
Gingival flap surgery also has the known deficiency to result in bone loss from the stripping away of the periosteum and hence the blood supply to the bone during the reflection of a surgical flap. It is well documented in the dental literature that gingival surgical flaps result in bone loss by the exposure of the underlying bone. Dr. Lindhe and co-workers have scientifically demonstrated that surgical flap elevation and removal of teeth leads to loss of the residual bone and the shape of remaining ridge after tooth removal. These undesirable anatomic changes to the bone make the placement of implants more complex and increases risk for patients.
For the reasons identified above, the trend toward minimally invasive surgical procedures has been developed toward the extraction of teeth. Examples of these changes include the use of micro-surgical instruments, periotomes and extraction forceps that do not require the reflection of a surgical flap to remove teeth. Ultrasonic (piezo technology) surgical instruments, dental lasers and rotary devices have been suggested as mechanisms to minimize trauma during the removal of teeth. It is generally accepted within the profession that a minimally invasive technique for tooth removal should be the standard of care.
In an attempt to minimize detrimental anatomic changes during the surgical removal of a tooth, a major effort is now underway to preserve the bone-zone and tissue-zone after tooth removal. The objective of the dental profession to preserve bone was a natural extension of a vast body of knowledge recently created on periodontal bone regeneration via the use of bone replacement substances. Examples of such efforts include autografts, allografts, xenografts and a variety of bone replacement materials that include; Bone Morphogenic Proteins (BMP's), Stem Cell Derviatives, Platelate Rich Proteins (PRP's) derived from the blood and numerous other biologic sources. Bone regeneration after periodontal disease is well established in the prior art. A deficiency of using bone replacement substances, is the inability to contain and protect these materials to exposure to the oral cavity during the critical healing phase, i.e. a fundamental inability to re-establish the all-important biologic-seal of the Tissue-Zone once a tooth is removed.
The use of barrier membranes for guided tissue bone regeneration (GTR) is known attempts to preserve and regenerate lost bone after periodontal disease. The use of membranes has more recently been applied to the regeneration and preservation of bone after tooth removal. Barrier membranes assist in creating a protective barricade to the bone-zone by excluding unwanted cells (connective tissue cells) to the healing site. This is an attempt to allow the body to more effectively refill a residual bony socket with bone cells (a.k.a. osteoblasts) known to be critical for bone growth. A general deficiency of using barrier membranes is the direct exposure of a barrier membrane that consequently lends to the inability to establish a soft-tissue seal. The exposure of the barrier membrane leads to plaque accumulation on the surface of the membrane that is impossible to clean. Once membranes become exposed to the oral environment, bacteria colonization on the surface of the membrane quickly spearheads an infection and/or failure of regeneration of bone. The primary cause of the exposure of the membrane is a lack of a soft-tissue biologic-seal after gingival flap surgery. The inability to re-establish a biologic-seal after the removal of a tooth has many repercussions to bone and soft tissue regeneration.
Loss of the biologic-seal of the tissue-zone also has a significant impact on soft-tissue changes to both the macro- and micro-anatomy of the gingiva. It is accepted in the dental literature that the loss of gingival attachment within the tissue-zone leads to the irreversible loss of the interdental papillae and the gingival architecture surrounding a tooth. There are currently no predictable surgical techniques available to correct the gingival changes to vertical height and horizontal dimensional after tooth removal. Much effort has been directed toward preserving the bone after tooth removal but far less effort has been applied to preserving the macro- and micro-anatomy of the tissue-zone after tooth removal.
As will be explained more fully in the following, the new method and arrangement of the present invention is an effective means to preserve the esthetic and anatomic architecture of the tissue-zone after tooth removal and the immediate placement of a dental implant. In addition, the present invention simultaneously and effectively re-establishes the all-important biologic-seal after tooth removal and immediate implant placement.
The understanding of using a minimally invasive technique as well as re-establishing a biologic-seal after tooth removal has been discussed but has not yet been made possible in all cases by known methods and apparatuses. In addition to these important concepts one further concept related to tooth removal is the technique of immediate dental implant placement after the extraction of a tooth/teeth.
The replacement of a tooth by a dental implant device is well known in the prior art. It is understood that there are two basic components to the dental implant device; the root-form component held within the bone-zone commonly referred to as the “dental implant” and a second component, the implant anatomic crown composed of an abutment and clinical crown. Both the abutment and clinical crown are typically placed superior to the crest of bone therefore within and superior to the tissue-zone. An implant prosthesis was first described as a surgical method and device that used a fully submerged, non-loaded healing period prior to the connection of the dental implant crown.
The advent of contemporary implant dentistry was first described by Prof. P. I. Branemark in the late 1970's and established the use of a titanium root-form screw to be inserted into the bone placed by using an atraumatic surgical technique described by this researcher/inventor. The method described by Branemark discussed the placement of the dental implant into jawbone of a fully edentulous ridge. He described a method in which the implant would be fully submerged and non-loaded during a healing period of 4-6 months after the dental implant was placed and covered within the bone. Pre-operative conditions therefore required a fully healed ridge in which teeth were previously removed. The method of using a submerged, non-loaded healing period for dental implants remains an approach still widely utilized today.
However, over the past 30 years alternative methods to implant placement have occurred. The following are different methods that have been advocated to the non-submerged, non-loaded implant healing technique.
Advantages and disadvantages will be briefly discussed for each technique.
Delayed, Submerged, Non-Loaded Implant Placement Method:
Defined as the method for placing a root-form dental implant into the jawbone. The implant is placed within the bone-zone initially. The pre-operative condition requires an edentulous ridge. The technique describes the placement of the implant into the bone at or below the crest of bone and it is fully covered by primary flap closure. An initial healing for a period of 4 to 6 months is required. A second surgery is required to expose the root-form implant and to connect a healing abutment. Second healing period of 2-3 months is required for soft-tissue. Final crown delivery occurs approximately 9 months after the start of treatment.
Deficiencies of this Method:
1. Requires multiple surgeries prior to implant crown placement.
2. Requires an edentulous ridge prior to implant placement into the bone-zone resulting in the irreversible changes to the soft-tissues of the tissue-zone.
3. Difficult to re-establish a biologic-seal after numerous surgeries and the connection of the implant crown.
4. Increased cost because of multiple surgeries and prosthetic components.
Delayed, Non-Submerged, Non-Loaded Implant Placement Method:
Defined as the method for placing a root-form dental implant into the jawbone exemplified by the Straumann, ITI implant company. The implant is placed within the bone-zone initially. The pre-operative condition requires an edentulous ridge. The technique describes the placement of the implant into the bone at or below the crest of bone or within the tissue-zone. A transmucosal healing cap component is used. A healing abutment or “cap” is placed onto the implant that is in direct contact with the soft-tissue during the initial bone-healing period of 4 to 6 months. A second surgery is not required to expose the root-form implant. Reformation of the tissue-zone is required. A connection between the implant and the healing abutment is within the tissue-zone.
Deficiencies of this Method:
1. Requires an edentulous ridge prior to implant placement into the bone resulting in the irreversible changes to the soft-tissues of the Tissue-Zone.
2. Requires flap surgery to place dental implant.
3. Difficult to re-establish a biologic-seal after surgery and the connection of the implant crown.
4. Difficult to re-establish soft-tissue anatomy to the state it was prior to tooth removal.
5. Healing abutment has an connection interface within the Tissue-Zone, which allows bacteria to adhere impeding wound healing.
6. Increased cost because of multiple components.
Immediate Root-Form Implant Placement:
A recent trend in implant dentistry that has occurred, that overcomes the deficiency of requiring multiple surgeries, is the immediate placement of a root-form dental implant directly into an extraction socket after tooth removal.
This method deviates from the original protocols established by Branemark and co-workers. The advantage to the simultaneous placement of a root-form dental implant after tooth removal is the reduction of the number of clinical procedures required as well as decreased treatment time. This technique eliminates the need to have the bone ridge healed after tooth removal consequently requiring fewer surgical procedures.
Immediate implant placement requires a mechanical locking of the root-form dental implant into the residual socket-site after a tooth has been removed. Mechanical locking refers to the root-form implant engaging undisturbed bone in an attempt to provide primary mechanical stability of the implant within the extraction socket. Immediate implant placement is highly desirable in comparison to delayed implant placement since it allows the immediate replacement of the tooth at a substantially reduced amount of time when compared to previous method of delayed implant healing.
Immediate Implant Placement Presents Numerous Risks and Deficiencies with Current Methods Used:
1. An inability to fully engage the entire remaining socket surface after tooth removal, thereby leaving a space (gap) between the surface of the implant and the surface of the remaining bone.
2. An inability to establish a biologic-seal to the overlying soft-tissues after a tooth has been removed.
3. An inability to retain bone regenerative materials if a residual gap remains between the surface of the implant and the bone socket.
4. An inability to establish a biologic-seal of the soft-tissue over a barrier membrane to protect and contain bone regeneration materials and the blood clot.
5. Inability to preserve the soft-tissue architecture of the gingival of the Tissue-Zone.
The deficiencies of achieving a predictable and esthetic long term outcome when using an immediate implant placement protocol can all be directly attributed to the inability to establish an acceptable biologic adaptation to create an effective biologic-seal in the tissue-zone of the remaining soft-tissue socket after removal of a tooth.
Immediate implant placement of a root-form dental implant has been shown to effectively osseointegrate by numerous authors (reference included herein). The residual gap that is present between the implant surface and the bone surface requires careful management whether a surgical flap is performed or a non-flapless minimally invasive extraction technique is used. In either of these two approaches, irreversible soft-tissue changes have been shown to occur with immediate implant placement after tooth removal. Changes within the tissue-zone are shown to occur as early as 2-3 days after the immediate implant placement.